Voice-directed aircraft navigation system

ABSTRACT

A navigation-by-communication system for informing the pilot of an aircraft as to the location of the aircraft along the approach-landing path, and along the runway during the critical period of landing and during take-off, especially during conditions of light and/or weather which prevent outside visual reference to terrestrial or celestial fixes.

0 United States Patent [191 [111 3,840,877 Crane Oct. 8, 1974VOICE-DIRECTED AIRCRAFT 2,097,072 10/1937 NAVIGATION SYSTEM 2,257,3209/1941 2,442,851 6/1948 [76] Inventor: Carl J. Crane, PO. Box 316,3,096,513 7/1963 Helotes, Tex. 78023 [22] Filed: J n 1972 PrimaryExaminerMaynard R. Wilbur [211 App]. Na: 262,528 AssistantExaminer-Richard E. Berger Related US. Application Data Continuation ofSer. No. 870,420, Oct. 16, 1969 abandoned.

References Cited UNITED STATES PATENTS 10/1932 Dieckman 343/112 R I 7 he1 l l 611% 1 5 "1 1 I 1 4 1|"? 1 Attorney, Agent, or Firm-Gilbert L.Wells ABSTRACT 1 Claim, 10 Drawing Figures AK -OFF 3 LAND 21 TAK gOFF 211 LAND 3 samiur 2 i -Tca.

PATENTED 81974 INVENTOR.

F IG. 7

FOR 3 GLIDE S OPE uulll IIIH FIG. 1

ou ou llll ll ow n wu ow ow VOICE-DIRECTED AIRCRAFT NAVIGATION SYSTEMThis is a continuation of application Ser. No. 870,420 filed Oct. 16,1969, now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention The instantinvention relates to ground and airborne electronic devices whichcombine, through systematic cooperative arrangement of the elements, toproperly inform the pilot of his location along the flight path duringapproach, landing, roll-out and/or take-off to or from a landing arearespectively. Normally the landing area is a runway. During clearweather and good light conditions the pilot may see the runway as it isapproached in flight. At night he sees the runway as outlined by lights,which are placed in various arrangements to assist in guiding him to therunway threshold and then along the runway. High performance aircraftwhich land at high speed require a long runway, and even in clearweather and good light the pilot depends on signs placed along therunway which indicate his distance already run, and left to run, alongthe runway. At night light patterns and colors serve a like nature. Whenfog or other weather condition obscures the runway the pilot at presenthas no measure of his location along the runway, and very little aidduring the final phase of an instrument approach to the runway.

2. Description of the Prior Art The contemporary employment of aircraftin day to day operation makes no use of electronic aids in the immediatevicinity of the runway to give the pilot position/distance informationduring the landing/take-off procedure. L

In my U.S. Pat. No. 3,307,191, entitled Aircraft Blind Landing Deviceand Flight Director System, there is disclosed the positioning of lowpower radio transmitters along the runway. As the landing aircraftpasses within a few feet of each transmitter its transmitted signal isreceived by the airborne receiver in such a manner as to cause anappropriate lamp to be lighted. The positions of the lamps are such asto indicate the successive positions of the aircraft along the runway.This array of lamps is positioned for ease of viewing within thepresentation of the flight instrument.

Another patent, U.S. Pat. No. 2,143,137 issued to D. S. Basim, et al.,disclosed the use of a boundary marker and only one other marker beaconplaced within the runway linear pathway, the purpose of which is asnoted in this patent on page 5, column 2, lines 23 to 33 inclusive. Thisdoes not anticipate the utilization of electronic transmitters placedand grouped as disclosed herein.

Another patent, U.S. Pat. No. 2,784,307 issued to W. D. Burton,describes in great detail the inner design of an improved marker beaconreceiver. One drawing in and Constantin D. Barbulesco, shows the liberaluse of marker beacons positioned in the line of approach to the runwayand at the far end of the runway; however the use defined a purposeother than informing the pilot visually or by voice of his location.

Accordingly, none of the prior art noted herein which exemplifies theuse of marker beacons employs them to continuously advise the pilot byvoice means of his position adjacent to and along the runway landingarea during the landing or take-0E procedure.

Obviously, with the exception of U.S. Pat. No. 3,307,191 to Crane theprior art does not exemplify an understanding of the problem facing theaircraft pilot in the touch-down/roll-out phase of the blind landing nordoes it propose a solution based on the real need to know constantly theaircraft location in its rapidly changing critical positions along thelanding area axis. Nothing in the prior art shows means for take-offguidance as the aircraft begins its roll, gains speed and reachescritical positions at which a take-off must be aborted.

SUMMARY Thus, with the deficiencies of some of the prior art defined,the instant invention proposes alternate means for continuously advisingthe pilot by voice from ground-based electronic transmitters, the locusof his aircraft with respect to the runway in the direction of flightduring approach/landing or take-off procedure.

The alternate means are:

l. The use of fixed or portable very low power transmitters placed alongand adjacent to the aircraft runway throughout its entire length atselected intervals so arrangedthat selected voice messages will betransmitted continusously, to be heard by the pilot of an aircraft bymeans of suitable radio receiver as the aircraft passes in the immediatevicinity of the ground-based transmitter. 2. The use of one or moreground-based automatic direction finders which will track anapproach-landing aircraft, or one taking off, in such manner thatswitching means connected to the tracking mechanism of the automaticdirection finder will operate to select appropriate stored voiceposition information that is continuously transmitted from a goundbasedelectronic transmitter to the communication receiver of the aircraftbeing tracked so that it may be heard by the pilot as he passes selectedsurface loci.

It is well known that effort is being made to supply precision DME(distance measuring equipment) with which to equip an aircraft to beused in making blind landings. This costly equipment employs, amongother items, complex airborne transponder devices to measure slant rangeto a ground-based device which itself is costly and which will berequired at both ends of a given runway if bi-directional use of therunway is required. This equipment provides a visual (counter type)readout device similar to an automotive odometer. The visual senses of apilot of an instrument landing aircraft are so heavily taxed that he hasneither the time nor concentration ability to read a fast-movingdistance counter, plus a fast-moving altimeter (of the digital or tapetype) and at the same time respond to the flight director indicationsand those of other instruments of the contemporary flight control panel.

By eliminating the digital counter of distance and substituting voiceconveyed position information the pilot is placed at greater ease, andhence is safer and more capable of responding to the visual indicatorsdisplayed on the instrument panel.

Accordingly it is the purpose of this invention to provideelectro-mechanical and electronic devices in combination, many of wellknown and proven reliability to insure voice-conveyed positioninformation to the pilot of an aircraft in the approach-landing and/ortake-off situation, and to accomplish this without adding any additionalelectronic device or equipment to the airplane equipped withconventional communication radio receivers and marker beacon receiver.

By the use of the alternative structure, almost any 10- cale can beserved, such as overwater approaches where it may be impractical tolocate surface based transmitters.

DESCRIPTION OF THE DRAWINGS FIG. l is a plan view of a landing runway,8,000 feet in length and 200 feet in width, drawn substantially toscale, showing radio transmitter locations to portray the importance ofposition information and the relationship of the transmitters locationsto a fast-landing aircraft.

FIG. 2 is a vertical view of the approach end of a runway which isassumed to be equipped with the conventional ILS (Instrument LandingSystem), the glide slope angle of which, for example, is 3. Thisportrays a location substantially 1,950 feet from the threshold at whichis located one of the transmitter sites called the boundary marker.

FIG. 3 depicts a schematic arrangement of the elements of the portablevoice-modulated transmitter assembly.

FIG. 4 shows the heat and rain shield that serves to protect theportable unit.

FIG. 5 shows the diagrammatic external circuitry of one of the severalpermanently installed voicemodulated transmitters.

FIG. 6 shows the general external appearance of the transmitter siteadjacent to and supplied with power from the circuitry serving one ofthe runway lights.

FIG. 7 shows the tape players and related switch which selects therunway transmitter to be activated for take-off or landing.

FIG. 8 shows a complete schematic array for the combined aircraft,runway, tracking direction finder and related switching device, tapeplayers and simple transmitter needed to transmit position informationto the pilot of the aircraft, by means of repeated selected wording todefine the locus of the aircraft.

FIG. 9 is an edge view of the photoelectric switch box cover withassociated lamp.

FIG. 10 is a second location for another automatic tracking directionfinder to be located in the event both landings and take-offs would bemade from the opposite direction on the runway from that shown.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Refer to FIG. 1 to note thatthe runway 10, in this description is served with 9 transmitters 11 onone side of the runway and 9 transmitters 11 on the other side of therunway. The transmitter itself employed in the structure of FIGS. 1, 3,5 and 6 is a simple voicemodulated crystal-controlled unit having lessthan 100 milliwatts power input to the r-f stage and transmitting on the75 mH portion of the radio spectrum to match the contemporary markerbeacon receiver now in use, or a separate receiver if so desired. Theperformance of the transmitter is empirically determined after carefulground and air tests. The transmitter weighs six ounces without powersupply, but including the halfwave antenna, which is oriented as shownin FIG. 1. The size of the transmitter lends itself to encapsulation ina sealed container 12 which is filled with an inert dry gas, andshielded electrically, and thermally, by means of the shield 13 (FIG. 6)In the form in which the transmitter is employed as shown in FIGS. 1 and6 it is arranged for plug-in connection to the conduit 14 which in turnmay be mechanically and electrically connected to selected runway lightsupport 16 where the transmitter and its associated power converter 17(transformer and rectifier) may share the electrical energy supplied tothe runway light 15. Since the runway lights will be activated duringobscure weather and/or light conditions by closing the switch 18 it isan economy to use the circuitry provided. In the event the transmittersare not needed, such as on clear nights, the switch 16, FIG. 5 and FIG.7 will remain open to deactivate the voice modulation output to thetransmitter circuits.

Voice modulation of the transmitter is supplied to the varioustransmitters by means of the playback of recorded voice. Voicerecordings may be stored on magnetic tape or disc or drum, or ontransparent film or disc or drum by means of light modulated recording.Refer to FIG. 7 in which are shown 4 multiple track gauged endless tapeplayers, each identified by the numerals 19, 20, 21 and 22. The multipletrack endless tape player 19 will supply, by means of ground telephonecable 23 the individual circuits to voice modulate the transmitters 11'for purpose of providing the pilot of an aircraft with needed positioninformation during take-off on runway 30. If a dense fog obscured allvision the pilot would secure the mid-line of the runway by means of theILS localizer and by moving on a heading of 210 proceed until he heardon the aircraft receiver the word zero being repeated in quicksuccession (about three words per second). He would then turn theaircraft to assume the runway heading of 030 and begin the take-offroll. His knowledge of the particular aircraft take-off performance willdictate that for each 1,000 feet of roll he must secure a proportionalairspeed indication, which if not achieved will require the aborting ofthe take-off. As the aircraft position enters a runway locus withinabout 200 feet of position 1 (FIG. 1) the spoken word one is heard,first increasing and then decreasing in volume until the aircraft passesfrom the range of the transmitter at that position. As each transmitterposition is reached and identified by the spoken word indicatingdistance along the take-off roll the pilot will prepare to rotate whenthe aircraft airspeed reaches an acceptable value, thereby completingthe lift-off.

The early part of the take-off roll is critical to safety, so theposition of the aircraft with respect to its performance is extremelyimportant. Accordingly as each position transmitter is passed, the pilotcan determine whether to continue or abort the take-off.

During the example just noted, the selector knob 25 would be set at the3 TAKE-OFF" position as shown in FIG. 7. For the purpose of landing onRunway 3 the knob 25 of the selector switch would be set at positionLAND 3 as shown in FIG. 7.

With this position selected the tape player will be activated in orderthat it will supply the position information needed in landing. All thetracks of the tape player 20 are activated to modulate the sametransmitters 11' but now including the transmitter 11" located at Bwhich is the boundary transmitter. It would be located as noted in FIG.2 at approximately 1,950 feet from the runway threshold (for a 3 glideslope configuration) and as the aircraft passes the boundary positionthe pilot would hear the word boundary repeated in quick succession.Experience with this system indicates that in an aircraft whose approachspeed is about 125 knots, five to six repetitions of the identifyingword are heard. After passing the boundary transmitter the aircraftenters the radiated space pattern of the runway threshold so that thepilot will hear the spoken word over to indicate the aircraft positionover the runway. Succeeding transmitter locations would be identified asnoted above with each thousand feet being identified by the spoken wordcorresponding to the distance along the runway.

After halting the roll-out should the aircraft stop, say, betweenposition 5 and position 6 the pilot may desire to taxi to position 7where a taxiway is located for movement to the parking ramp. In obscureweather the expeditious ground operation of the aircraft to clear therunway is important and is aided by the runway transmitters if guidelights cannot be seen.

In FIG. 2 the approximate location of the ILS middle marker MM is shownin relation to the boundarry marker BM and the runway threshold.

In the event runway 21 is to be used for flight operations the selectorknob will be adjusted to the proper position for LAND 21" or 21TAKE-OFF. In this event all the operations described above for runway 3will be valid and the transmitters l1 and 11" at position B will beactivated. This will place in operation the tape player-amplifier units21 and 22 and energize the telephone cable 26 to connect with the cable27 underground to the various transmitter positions 11 as the cable 23connects with the cable 28 to energize the transmitters 11' and 11" atposition B.

It will be noted that certain simplifications can be made to reduce thenumber of transmitters by cross-use but in the interest of safety someduplication of the system is considered vital.

There may be situations where a limited number of portable runwaytransmitters may be used at small or hastily set up landing areas, orneeded for emergency or temporary use. To satisfy these possible needsreference is made to FIG. 3 which shows a complete runway transmitterwhich includes the transmitter 29, the tape player 30, two batteries 31and 32, battery test meter 33 and switch panel 34, suitably enclosed ina ventilated container 35, with shelf 36 and weather and heat shield 37equipped with handle 38 and tubular extensions 39 which engage the legextensions 40 of the container.

Another form of the invention is shown schematically in FIGS. 8 and 9.In this embodiment of the voicedirected fixing of position during eithertake-off or landing use is made of any precise method of tracking theaircraft in its path along the localizer 48 of the ILS (instrumentlanding system), while in flight, and along the runway 47 duringroll-out as well as during take-off roll.

Several methods of tracking the aircraft may be employed, namely:

1. By primary radar 2. By secondary radar, transponder equipped 3. Bylow frequency automatic direction finder, ne-

cessitating a non-directional low power transmitter aboard the aircraft4. By VHF direction finder utilizing the normal aircraft communicationtransmitter In FIG. 8 the servo-driven rotating shaft 41 of theautomatic direction finder is connected to the shaft of a rotatingswitch 42, in this instance a photoelectric shutter switch. As theaircraft 43 is tracked in its approach path the photoelectric shutterswitch will successively energize each of the relays 44 as the aircraftsuccessively passes the position A to K inclusive. In so doing the pilotof theaircraft will hear, for about 1% seconds the quickly spoken wordsin succession as follows:

Five four three boundary near over one two three four five In thisinstance the runway of FIG. 8 is 6,000 feet long. The first heard spokenword five indicates the aircraft to be 5,000 feet from the threshold,and approaching the average location of the middle marker of the ILSaid. Since the tracking angle (with the runway axis) from the directionfinder is at the locus of the boundary marker (position D) it is at thisposition where the greatest accuracy of line of position obtains. Onlyslightly less accurate is position E and F near and at the threshold.The probable error is well within practical limits at all positionfixes.

On very long runways it may be desirable to add another tracking station45 in addition to the tracking station 46.

As the direction finder tracks the aircraft to position A, its shaft 41rotates the cup-shaped shutter 49 within and close to the cylindricalwall 50 of the photoelectric switch. Light from the lamp 51 (FIG. 9)will be admitted through both the aperture 52 of the shutter and theslit 53 in the wall 50. For about 1% seconds this will activate thephotoconductive cell 54 which is light shielded from adjacent photocellsby the bulkhead 55. Each of the II photocells is light-shielded in likemanner from the others and from external light by the circular cover 56which supports the lamp 51. The power source 57 supplies current to eachphotocell, one terminal of which is grounded to a common ground whichalso serves each of the relays 44. The other terminals of the photocellslead to a series of binding posts 58 which in turn serve the coils ofthe relays 44. As each relay is activated, so is its matching tapeplayer of the group of tape players 59. The output of each tape playerconnects to a common lead 60 which is the leadin to the modulator of thesingle communication transmitter used to communicate positioninformation to the aircraft. It may be that one special frequency may beallotted by the Federal Communication Commission for this particularservice.

I claim:

1. In combination with an Instrument Landing System having a glide slopeangle of about 3 for take-off and landing to the runway, an aircraftrunway distance monitor system for providing an audible and vocalindication of the longitudinal position of the aircraft along therunway, said monitor system comprising:

a plurality of low-power voice modulated portable transmitters with halfwave antenna each posisaid low-power voice modulated transmitterincluding endless magnetic tape reproducer means for playing selectedwords for transmission at each of said transmitters which indicate bythe word and repeating of said words, the longitudinal position of theaircraft when received by a receiver in the aircraft;

said low-power transmitter broadcasting a distance of about 200 feet inthe radiospectrum and being a voice modulated crystal controlled unithaving less than 100 milliwatts power to the r f stage whereby the weakaudio signals of all of the transmitters in the same row permit a clearrepetition of the voice signal for a short distance of about 200 feedand less than 300 feet within a succession of said signals along therunway, this distance defining a proximate range for each transmitter;

receiver means in the aircraft including an audio indicator means forsuccessively receiving the radiated voice signals from said transmitterwithin the proximate range for each transmitter, the voice signalreceived first increasing in volume as the aircraft approaches theselected transmitter and then decreasing in volume as the aircraftpasses beyond the proximate range of said transmitter; and,

a selector switch means for the rows of said runway transmitters havingtwo positions, one for take-off and one for landing, the setting of saidswitch energizing words for transmission from said endless tapereproducers selected either for aircraft takeoff or selected foraircraft landing.

1. In combination with an Instrument Landing System having a glide slopeangle of about 3* for take-off and landing to the runway, an aircraftrunway distance monitor system for providing an audible and vocalindication 0f the longitudinal position of the aircraft along therunway, said monitor system comprising: a plurality of low-power voicemodulated portable transmitters with half wave antenna each positionedat marker locations fitted with lights on each side of said runway, saidmarker locations being spaced at regular intervals along said runway andopposite each other serving as runway marker lights with a power sourceand switching means for energizing and actuating said lights; saidlow-power voice modulated transmitter including endless magnetic tapereproducer means for playing selected words for transmission at each ofsaid transmitters which indicate by the word and repeating of saidwords, the longitudinal position of the aircraft when received by areceiver in the aircraft; said low-power transmitter broadcasting adistance of about 200 feet in the radiospectrum and being a voicemodulated crystal controlled unit having less than 100 milliwatts powerto the r - f stage whereby the weak audio signals of all of thetransmitters in the same row permit a clear repetition of the voicesignal for a short distance of about 200 feed and less than 300 feetwithin a succession of said signals along the runway, this distancedefining a proximate range for each transmitter; receiver means in theaircraft including an audio indicator means for successively receivingthe radiated voice signals from said transmitter within the proximaterange for each transmitter, the voice signal received first increasingin volume as the aircraft approaches the selected transmitter and thendecreasing in volume as the aircraft passes beyond the proximate rangeof said transmitter; and, a selector switch means for the rows of saidrunway transmitters having two positions, one for take-off and one forlanding, the setting of said switch energizing words for transmissionfrom said endless tape reproducers selected either for aircraft take-offor selected for aircraft landing.